Gastrointestinal function following endurance exercise under different environmental temperatures

We determined the effects of different environmental temperatures on exercise-induced gastrointestinal (GI) damage and delayed gastric emptying (GE) rate.

Eleven trained males completed three trials on different days, consisting of (1) exercise in a thermoneutral environment (CON, 23 °C), (2) exercise in a hot environment (HOT, 35 °C), and (3) exercise in a cold environment (COLD, 10 °C). The subjects performed high-intensity interval-type endurance exercises in all trials. Blood intestinal fatty acid binding protein (I-FABP) levels was determine before and after exercise. We evaluated T_max (time when the ¹³C-excretion/h reached a maximum level) as an indication of the GE rate during post-exercise.

Rectal temperature during exercise was significantly higher (P < 0.001) in the HOT (38.7 ± 0.3 °C) trial compared with the CON (38.2 ± 0.3 °C) and COLD (38.2 ± 0.3 °C) trials, with no significant difference between the CON and COLD trials. Plasma I-FABP level after exercise (relative to the pre-exercise level) were significantly greater (P = 0.005) in the HOT trial (92.9 ± 69.6%) than in the CON (37.2 ± 31.6%) and COLD (37.6 ± 41.8%) trials. However, there was no significant difference between the CON and COLD trials. Moreover, the T_max was delayed significantly (P = 0.006) in the HOT trial compared with the CON and COLD trials, with no significant difference between the CON and COLD trials.

GI function following endurance exercise was similar between thermoneutral and cold environments, while endurance exercise in a hot environment exacerbated GI function compared with thermoneutral and cold environments.